Throughout the United States and in most of the world, electrical energy is provided to various consumers over electrical transmission or power lines supported by poles or towers. The area beneath and adjacent the electrical transmission lines must be kept substantially free of tall vegetation, such as bushes, brush, and trees. Such a zone is referred to herein as a "right-of-way". The area beneath and adjacent some telephone transmission lines supported by poles must be kept in a similar manner. Furthermore, many highways and roads include a right-of-way on either side that must also be kept in a similar manner.
After a right-of-way for electrical transmission lines or telephone transmission lines is initially cut through a wooded or vegetated area of land, the utility right-of-way must be maintained substantially vegetation-free. Particularly, vegetation such as bushes, brush, and trees must be cut to prevent them from growing into and interfering with the transmission lines. Additionally, the cut debris must be ground up or mulched. The reason for the grinding or mulching is two-fold. First, the utility right-of-way must be sufficiently clear to allow travel over the ground by repair and maintenance crews. Second, and more important, the utility right-of-way must not contain cut debris of a size that would interfere with the hydraulic lines and equipment contained on utility transmission line repair trucks. The safety of the personnel is jeopardized if the rights-of-way include cut debris of sufficient size to cause damage to the hydraulic drive systems or hydraulic lines of these repair trucks, or to cause any other type of mechanical damage. Thus, it is necessary not only to cut the debris in utility rights-of-way, but also to grind or mulch it so that the cut debris is of sufficiently small size.
Numerous conventional mowing or cutting devices are known. One conventional brush and tree cutter is shown in U.S. Pat. No. 3,483,905 to Lawrence. The Lawrence device is expensive to build, and expensive and difficult to maintain and keep operational. The Lawrence device also suffers from safety problems. One safety problem is that the protective bar and partial blade guard of the Lawrence device do not prevent debris cut by the rotating blade from flying out of the device. The Lawrence device also does not provide protection in the event of a mechanical failure of the rotating cutting blades.
Another safety problem of the Lawrence device arises because the ends of the protruding bar are free and unprotected. As the Lawrence device is operated, the unprotected, protruding free ends of the protective bar snag or grab wires, vines, fences, and the like. This problem is particularly acute with respect to guide wires for utility poles. The free ends of the Lawrence protective bar routinely snag on such guide wires. As a result, the protective bar can be pulled off the Lawrence device, and the utility pole can even be pulled down. This problem leads to damage to the Lawrence device, to the utility pole, and to the transmission lines, and can even lead to injury or death. When the protective bar is pulled off, it typically falls down into the blades, creating hazardous flying debris. The problem of the protective bar being pulled off is so common that a majority of users remove the protective bar for use of the Lawrence device.
Another drawback of the Lawrence device for use in clearing and maintaining utility rights-of-way is that it is not capable of grinding or mulching cut debris. Therefore, operation of the Lawrence device on a utility right-of-way would require at least a second pass over the terrain because cut debris that is too large poses a safety hazard for crews repairing or maintaining the utility transmission lines.
Another conventional device is disclosed in U.S. Pat. No. 4,445,312 to Cartner. The ends of the Cartner device are open, allowing cut debris to fly from the device at either end. The side-mounted boom configuration of the Cartner device makes the open ends a particular safety risk because the prime mover is not in a position to stop debris that flies from either end of the device, debris that could include a blade. Like the Lawrence device, the Cartner device is also not configured to grind or mulch cut debris. Thus, operation of the Cartner device on a utility right-of-way also requires at least a second pass over the terrain to grind or mulch the cut debris.
A more effective kill of vegetation can be obtained if chemicals, such as herbicides and the like, are sprayed onto the cut stems and stalks since the chemical then directly acts on the roots. This approach minimizes re-growth of the vegetation with a significantly reduced quantity of chemicals. However, when dispensing such chemicals, it is necessary to minimize wind drift or overspray of the chemicals to other areas. In the conventional sprayer/cutter apparatus shown in U.S. Pat. No. 5,237,803 to Domingue, Jr., this is achieved through the use of mated circular shields and perimeter guards. However, the Domingue device requires precise spacing between the circular shield and the blades, as well as critical positioning of openings in the circular shield for release of the pesticide spray. This makes the device harder and more costly to manufacture. The Domingue device is alto expensive and difficult to maintain. The intricate shield arrangement of this device is damaged by the large debris moving at high speed as the cutter operates.
Thus, there is a need in the art for a device that is safe to operate, and that is capable of mowing, cutting, and mulching vegetation in a single pass over the terrain. There is a further need for such a device to include an apparatus that is easy and less costly to manufacture for spraying chemicals to obtain a more effective kill of the vegetation, while preventing wind drift and over-spray.